Ocular blood flow in patients with obstructive sleep apnea syndrome (OSAS)

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BACKGROUND: Sleep-related disorders are among the important risk factors for neurovascular diseases. Obstructive sleep apnea syndrome (OSAS) is characterized by snoring, excessive daytime sleepiness, and insomnia. Our aim was to investigate the presence of glaucoma in patients with OSAS and to reveal vascular pathology related to the pathogenesis of glaucoma in those patients. PATIENTS AND METHODS: The study included 31 patients with OSAS and 25 control subjects. Orbital Doppler ultrasonography was used to determine the resistivity index (RI) in the ophthalmic artery and central retinal artery. All patients and controls underwent perimetric examination. RESULTS: The prevalence of glaucoma in the group of patients with OSAS was 12.9% (4/31); all of these 4 patients with glaucoma were in the "severe" OSAS group. No statistically significant difference was found between ophthalmic artery resistivity index (OARI), central retinal artery resistivity index (CRARI), and intraocular pressure (IOP) between patients and controls (p > 0.05). There was a positive correlation between OARI and mean defect (MD), CRARI and MD, and CRARI and loss variance (LV) values (p < 0.05). There was also a positive correlation between IOP and the apnea-hypopnea index (AHI) (p = 0.001). CONCLUSIONS: In patients with OSAS, a high prevalence was found and it is interesting to note that all of the four glaucoma patients were in the severe OSAS group. The positive correlation observed between IOP and AHI suggests that increased IOP values may reflect the severity of OSAS. The positive correlation between OARI and MD and also between CRARI and MD as well as LV suggests that visual field defects may be due to optic nerve perfusion defects and these field defects also increase as the RI increases.